Raccoon River Bridge, Rainbow Bend Access, Marsh Rainbow Arch Bridge
Concrete Marsh Arch
National Register of Historic Places status:
Iberia Avenue over the North Raccoon River, 2.7 miles southwest of Lake City, Section 25, T86N-R34W (Jackson Township)
Known locally as the Lake City bridge, this concrete Marsh arch bridge spans the North Raccoon River in the southwestern corner of Calhoun County. Consisting of three 80-foot concrete spans supported by a concrete substructure, the bridge's overall length is 271 feet. The bridge dates from 1913, when the Calhoun County Board of Supervisors decided to replace the existing zane bridge, a pinned Pratt through truss built in 1892 by the King Bridge Company. The supervisors requested a design for a replacement structure from the State Highway Commission, which in January 1914 completed the drawings for a three-span pony truss bridge on concrete piers and abutments. At this time, the county also commissioned Des Moines engineer James B. Marsh to design a three-span concrete arch for the crossing. Marsh's plans featured the through arch design that he had developed two years earlier, with his trademark slotted guardrails and paneled concrete bulkheads. After Marsh's design was approved by the state highway commission in March 1914, competitive bids were solicited on both designs. In April, a contract was awarded to the Iowa Bridge Company to build the concrete arch version for the Lake City bridge for $10,970 - some $2,000 below the amount estimated by the county engineer. IBCo began work on the substructure soon thereafter, eventually shipping in five carloads of cement and three carloads of steel and using some 1,000 cubic yards of gravel obtained from a nearby riverbank, according to local sources.
The Lake City bridge was the third of Marsh's namesake rainbow arch bridges built in Iowa. As he would for other bridges in the state, Marsh offered his design to Calhoun County as an alternative to the standard engineering of the state highway commission. It would also serve as a demonstration of his arch in a multiple-span configuration. "This bridge is being made as a sample," the Lake City Graphic reported in 1914. At the time of its completion later that year, Marsh boasted that it was "the largest bridge of its type in the United States."
The Lake City bridge is historically significant on a local basis as an important crossing of the North Raccoon River in southwest Calhoun CO. In a broader scope, it is technologically significant as a formative exercise in the career of one of Iowa's most distinguished engineers, James Marsh. The Lake City Rainbow Arch Bridge is distinguished among these by its early construction, its multiplicity of spans and its formative role in the development of this indigenous structural type. [adapted from Fraser and Crow-Dolby 1992]